PartitionSpec.Builder does not support column name case-insensitivity

[sl255051]

Apache Iceberg version

None

Query engine

None

Please describe the bug 🐞

PartitionSpec.Builder can only build a partition spec when column names match in a case-sensitive way.

I've written a unit test (included below) that reproduces the issue. You can add this unit test to the TestPartitionSpecInfo class. The test fails at PartitionSpec.builderFor(schema).identity("DATA") because the schema's column is defined with the name "data" but the builder is looking for "DATA".

  @TestTemplate
  public void testSpecInfoPartitionedTableCaseInsensitive() {
    PartitionSpec spec = PartitionSpec.builderFor(schema).identity("DATA").build();
    TestTables.TestTable table = TestTables.create(tableDir, "test", schema, spec, formatVersion);

    assertThat(table.spec()).isEqualTo(spec);
    assertThat(table.spec().lastAssignedFieldId()).isEqualTo(spec.lastAssignedFieldId());
    assertThat(table.specs())
            .containsExactly(entry(spec.specId(), spec))
            .doesNotContainKey(Integer.MAX_VALUE);
  }

[sl255051]

I have created a PR to address this issues. Please have a look at #10678

[sl255051]

This issue has been fixed with the following PR #10678